SEOUL, South Korea — An elephant in a South Korean zoo is using his trunk to pick up not only food, but also human vocabulary.

An international team of scientists confirmed Friday what the Everland Zoo has been saying for years: Their 5.5-ton tusker Koshik has an unusual and possibly unprecedented talent.

The 22-year-old Asian elephant can reproduce five Korean words by tucking his trunk inside his mouth to modulate sound, the scientists said in a joint paper published online in Current Biology. They said he may have started imitating human speech because he was lonely.

One of the researchers said there is no conclusive evidence that Koshik understands the sounds he makes, though the elephant does respond to words like “anja.”

Everland Zoo officials in the city of Yongin said Koshik also can imitate “ajik” (not yet), but the researchers haven’t confirmed the accomplishment.

Koshik is good with vowels, with a rate of similarity of 67 percent, the researchers said. For consonants he scores only 21 percent. Researchers said the clearest scientific evidence that Koshik is deliberately imitating human speech is that the sound frequency of his words matches that of his trainers.

Vocal imitation of other species has been found in mockingbirds, parrots and mynas. But the paper says Koshik’s case represents “a wholly novel method of vocal production” because he uses his trunk to reproduce human speech.

In 1983, zoo officials in Kazakhstan claimed that a teenage elephant named Batyr could reproduce Russian to utter 20 phrases, including “Batyr is good.” But there was no scientific study on the claim.

Researchers believe Koshik learned to reproduce words out of a desire to bond with his trainers after he was separated from two other elephants at age 5.

Koshik emerged as a star among animal enthusiasts and children in South Korea after Everland Zoo claimed in 2006 that he could imitate words, two years after his trainers noticed the phenomenon. His growing reputation prompted Austrian biologist Angela Stoeger-Horwath and German biophysicist Daniel Mietchen to study him in 2010, zoo officials said.

President Donald Trump's latest barrage of tweets attacking investigations into Russian meddling in the 2016 election stretched the bounds of credulity, from false claims that "no crime" had been uncovered to assertions that his campaign had been cleared of collusion with Russia.